Separable electrical connectors using isotropic conductive elastomer interconnect medium

ABSTRACT

An electrical connector using an isotropic conductive elastomer as the interconnect medium.

RELATED APPLICATIONS

This is a continuation patent application of Ser. No. 12/799,712 whichis a divisional patent application of non-provisional application Ser.No. 12/316,677 filed on Dec. 16, 2008 and claims priority under 35 USC120 which in turn is a non-provisional application of provisionalapplication Ser. No. 61/008,262 filed on Dec. 18, 2007 by James Russelland of provisional application Ser. No. 61/009,272 filed on Dec. 27,2007 by James Russell and claims priority thereof.

BACKGROUND OF THE INVENTION

1. Field

The present invention relates to an electrical connector. Theseconnectors electrically connect an adaptor board to a main circuit board(main board) where it is necessary to convert the coarse pad arrangementof one with a fine pad arrangement of the other through the use of aninterposer board. In particular, the present invention relates to anelectrical connector using isotropic conductive elastomers on both sidesof a modified printed circuit (PC) board to ensure good electricalcontact while freeing the PC board for the ability to route traces onthe interface sides of the PC board.

2. The Related Art

U.S. Pat. No. 6,702,587 to Weiss et al. (the '587 patent) relates to anelectrical connector using an anisotropic conductive elastomer (ACE).The ACE is provided in sheet form and conducts electricity in the z axison a consistent pitch over the entire surface of the conducting region.This prevents the device in the '587 patent from having the ability toroute conducting traces on the interface sides of the adaptor board andthe main board.

SUMMARY

The present invention provides an electrical connector using anisotropic conductive elastomer as the interconnect medium. The isotropicmaterial is preferably placed on conductive lands of both sides of amodified PC board to permit routing of conducting traces on theinterface sides of the adaptor board and the main board.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded sectional view of a first embodiment of thepresent invention;

FIG. 2 A is an exploded sectional view of a second embodiment of thepresent invention in which the number of pads is different from that ofthe embodiments in FIGS. 1, 4 and 5;

FIG. 2 B illustrates the trace routing where the trace routing ispossible on the interface layers of the adaptor board, it beingunderstood that although not shown the trace routing can be similarlyeffected on the interface layers of the main circuit board instead ofthe adaptor board; in accordance with the embodiments of FIG. 1, FIG. 4and FIG. 5 of the present invention;

FIG. 3 is the modified PC board of the embodiment of FIG. 1;

FIG. 4 is a third embodiment of the present invention in which there isno need for a modified PC board and the adaptor board has lands that arecoated with isotropic elastomeric material; and.

FIG. 5 is a fourth embodiment of the present invention in which there isno need for a modified PC board and the main circuit board has landsthat are coated with isotropic elastomeric material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring now to the drawings of FIGS. 1-3, FIG. 1 illustrates theelectrical connector of the present invention in which the connector hasa mechanical compression structure 5, an adaptor board 6 with connectinglands or pads 7, and a modified PC board 8 with isotropic elastomermaterial formed on lands on both sides of the PC board 8; and a maincircuit board 10 having connecting lands 11. A socket 5 a in thecompression structure 5 is adapted to house a test circuit such as anintegrated circuit (IC) chip. Pins 5 b provided for making electricalconnections in the IC chip housed in socket 5 a with pads 7 of theadaptor board 6. The connecting lands or pads 7 of the adaptor board 6and of the connecting lands 11 of the main circuit board 10 are placedinto contact with isotropic elastomer material 9 located on the lands orpads 9 a of the modified PC board 8 when the adaptor board 6 and the PCboard 8 and the main circuit board are compressed together by themechanical compression structure. The connecting pads Thus the modifiedPC board 8 by placement of the isotropic elastomeric material 9 thereonserves as an isotropic pad defined connector 8.

By compressing the boards together it is possible to provide anelectrical connection between the adaptor board and the main circuitboard 10 and convert the pads on each board's surface connection fromcoarse to fine or vice verse by use of the intermediate connector—themodified PC board with isotropic elastomer. By using lands on both sidesof the PC board the connection is good while increasing the routingdensities and deceasing cost by only placing isotropic materials at padlocations rather than throughout the entire surface of the connectingregion as with the '587 patent.

In addition to converting the pitch by connecting fine pads to coarsepads and vice verse, the present invention also provides for reroutingthe electrical connections from the pins 5 b 1-7 connected to the pins 4of the test circuit 3 (such as an IC chip 3) housed in the socket 5 a ofthe mechanical compression structure 5 to the pads 7 of the adaptorboard 6 and to the pads 11 of the main circuit board 10. As shown inFIG. 2A, the adaptor board 6 can be rerouted so that its path or traces12 do not have to connect to the corresponding land or pad 11 on themain circuit board 10 nor does it need to translate pitch. Thus pin 5b-1 on structure 5 can be connected to one pad 7-1 on a first side 6 aof the adaptor board 6 and pad 7-1 is rerouted via a trace 12 to connectto the pad 7-6 rather than the first land 7-5 on a second side 6 b ofthe adaptor board 6. The pad 7-2 is then connected to the pad 11-2 onthe opposing surface 10 a of the main circuit board 10. Any possiblere-routing can be effected in this way. In this way the presentinvention permits re-routing of circuitry as desired. In addition thenumbers of pads for the adaptor board 6 and for the main circuit board10 can vary as needed and are different for this embodiment than for theembodiment in FIG. 1. In addition in this embodiment of FIG. 2A there isno need for a modified PC board 8 as in FIG. 1 as is also the case inthe embodiment of FIG. 5.

FIG. 2 B illustrates one possible illustration of an enhanced tracerouting 12 of the present invention. As a result of the placement of theisotropic lands 9 on each side of the modified PC board 8 trace routing12 is possible in and around connecting land arrays on interface layersbetween the modified PC board 8 and the adaptor board 6 and between themodified PC board 8 and the main circuit board 10. This provides forrouting density in circuit on both sides of the modified PC board 8 ofthe present invention. In addition this provides a more cost effectivesolution than the aforementioned prior art proposal. The modified PCboard is not shown in the illustration of FIG. 2A. It is understood thatthis feature of the re-routing of the adaptor board 6 works for theembodiments of FIGS. 1, 4 and 5.

FIG. 3 illustrates the modified PC board 8. The PC board 8 is modifiedby placing lands with isotropic material on both surfaces of the PCboard 8 as shown. While FIG. 3 shows one surface it is understood thatthe other surface is similarly arranged. The isotropic material can beisotropic paste placed on pads of the pads on both sides of the modifiedPC board 6

FIG. 4 illustrates a second embodiment in which there is no need for amodified pc board between the adaptor board and the main circuit board.Instead the lands on the surface of the adaptor board opposingly facingthe lands of the main circuit board are coated with an isotropicelastomer material such as isotropic elastomer paste. Thus instead ofcoating the pads of a modified PC board 8, as was the case in FIG. 1 ofthe present disclosure, the lands of the adaptor board 6 facing thelands of the main circuit board 10 are coated with the isotropicelastomer paste.

FIG. 5 illustrates a third embodiment in which there is no need for amodified PC board 8 between the adaptor board 6 and the main circuitboard 10. Instead the lands on the surface of the main circuit board 10opposingly facing the lands of the adaptor board 6 are coated with anisotropic elastomer material such as isotropic elastomer paste. Thusinstead of coasting the lands of a modified PC board 6, as was the casein FIG. 1 of the present disclosure, the lands of the main circuit board10 facing the lands of the adaptor board 6 are coated with the isotropicelastomer paste.

FIG. 2 B illustrates one possible illustration of an enhanced tracerouting 12 of the embodiments of FIGS. 4 and 5 of the present inventionas it has illustrated for the embodiment of FIG. 1. Pads can be 7 or 11depending upon where the isotropic paste placed. Therefore is theisotropic material such as isotropic paste is placed on the pads 7 ofthe adaptor board 6 then trace re-routing must be done on the maincircuit board 10 as described previously with respect to the adaptorboard 6. Similarly, if the isotropic material such as isotropic paste isplaced on the pads 11 of the main circuit board 10 then trace reroutingmust be done on the adaptor board 6.

While presently preferred embodiments have been described for thepurposes of the disclosure, it is understood that numerous changes inthe arrangement of apparatus parts ca be made by those skilled in theart. Such changes are encompassed within the spirit of the invention asdefined by the appended claims.

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 7. An electrical connector for providing an electricalconnection between an adaptor board and a main circuit board,comprising: an interconnect medium having an isotropic conductiveelastomer that provides an electrical connection between said adaptorboard and said main circuit board and said electrical connector isformed as lands on a surface of said adaptor board opposingly facinglands of said main circuit board where said lands of said adaptor boardare coated with an isotropic elastomer material wherein electricalconnections from the pins of a test circuit are rerouted to the pads ofthe adaptor board and the lands of the adaptor board and the maincircuit board by rerouting the electrical connection from an uppersurface of the pads on the adaptor board to pads of a bottom surface ofthe adaptor board.